Hi Beemer folk,

I'm currently looking at a 1995 R80GS in very tidy nick. Petrol here in Turkey is very expensive therefore MPG is a consideration. Ridden steadily what MPG could I hope to achieve? Also, are there any known weak points I should be looking out for?

Thank you very much.

Cheers,

Dicky

I have a 94 which returns 45-60 mpg depending on how it is ridden. High revs really sucks the fuel.

Crossing Africa rarely exceeding 50 mph 2 up we regularly got 60+ on good fuel


75-80mph and it's down to 50

Cane it and start doing 6k revs a lot and it drops dramatically

We don't know much about imperial measures down here, but my 1983 R 80 G/S (same engine) gets nearly 20 km/Litre, if I take it very easy (meaning by puttering around the countryside at 80km/h max)

Anywhere near a town that drops quite a lot. in any kind of stop start traffic it can easily go down to around 16.5 km/L.

My average is actually somewhere between both figures, usually 2 up, on long journeys and not going too slowly. Usually this means hitting reserve after around 280 km, with my 19L tank

The 800cc version is the most thirsty of all the air-cooled beemer models...

There are claims that their 800cc engine use about 0.45-0.5L/10km, but to faire... I still have to see an 800cc use that little gas...

My R80 1984 used more than 0.8L/10km when I bought it from the police. The best mileage that I have managed to get out of it is 0.57L/10km. When I did get this mileage I had 44/40 highflow valves, lowered the heads by about 0.8mm (=> about 10.3:1 compression ratio), dual ignition.

What did make a significant change was the installation of the HPN 5th gear sprocket. It resulted in about 0.02-0.03L/10km less consumption.

Here is the thing.
1000cc will use less fuel in most instances - since it revs less, and need less energy thanks to the far higher torque. The newer like the one you look at have 8.2:1 compression ratio, which allows for less good fuel. The down-side is that lower compression ration will result in higher fuel consumption...

You should anticipate that the 800cc will use anything between 0.5L/10km to 0.7L/10km at 90km/h constant speed on a "autobahn". You should not accept higher milage than 0.6L/10km, but if the bike uses more... it will most likely take a lot of work to find the causes and correct them. I 've spent over one decade (>10 years) trying to figure out why my 800 is so darn thirsty. Bought it in 1991 - I've still searching for the reason/causes...

Remeber that the petrol cools the valves and seats, so should you get the bright idea to install smaller jets... it will be best to carry a spare engine...

Looking at your question and that you do point-out that the petrol cost is an issue, I will have to recommend that you look at water-cooled engines since these usually runs at a far better mileage than the air-cooled.

Changing the bing-carbs to throttle carbs like Dell'Ortos 34, Mikuni 34 or Keihan 34 for the 750-800cc series will result in far better milage. You can expect 0.1L/10km improvement. With tuning it is reasonable to achive up to about 0.15L/10km improvement over the bing-carbs. Side-effect is much better gas-respons, enginebraking and idle. Down-side - quite a bit of work to install... there is a wire-split under the tank... the throttle lift is not large enough (I modified my system and still I get only about 80% lift of the throttle).
K&N air-filter will give about 0.01L/10km improvement over the stock paper airfilter; but,... if you drive in dusty/sandy areas... you ought to only use the paper air-filters(!)...

__________________
Drive Safely,
Albert

Thank you for your very much for your replies and Albert for a particularly useful analysis.

I currently have a couple of old Yamaha 600's and one of the newer XT660R's with fuel injection. In light of what has been said I will be staying with the XT660R for distance touring.

Thanks again for taking the time.

Cheers,

Dicky

Hello David,

I jointly own and run Bike Turkey in Gocek Bike Turkey Home, if you need a good mechanic for the BM, there is a great guy in Fethiye - he does all our BM's - even the new one's.

Robert
robert@bike-turkey.com

Hi Dicky,

I really like the old Yamaha XT600. Quite fuel efficient. Good engine power. Does well on longer trips.

The newer XT660 is said to have some irritating down-sides, and to be more thirsty. That could be just bad talk, but I've heard it from all continents and all ages of drivers...

I would choose to stick to the old XT600 and to do the appropriate tune-ups like an oil-cooler, wind-defectors/collectors (for cooling the engine and keeping the driver from too much draught.

However... this is a BMW side, so... I'm way off topic!

The beemers are very good bikes. Some modifications and they are excellent. The costs vary from moderate to less comfortable costs... If I recall correctly the XT600 weighs in at around 170kg wereas the all stripped down beemers starts at 220kg - those 50kg is a lot of load once the bike tips over (which bikes do have a nasty tendency of doing...).
My R80 tips the scale at around 270-280kg...

__________________
Drive Safely,
Albert